/*
Source : https://leetcode.com/problems/guess-number-higher-or-lower/
Author : nflush@outlook.com
Date   : 2016-08-01
*/

/*
374. Guess Number Higher or Lower

    Total Accepted: 11366
    Total Submissions: 36174
    Difficulty: Easy

We are playing the Guess Game. The game is as follows:

I pick a number from 1 to n. You have to guess which number I picked.

Every time you guess wrong, I'll tell you whether the number is higher or lower.

You call a pre-defined API guess(int num) which returns 3 possible results (-1, 1, or 0):

-1 : My number is lower
 1 : My number is higher
 0 : Congrats! You got it!

Example:

n = 10, I pick 6.

Return 6.

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*/

// Forward declaration of guess API.
// @param num, your guess
// @return -1 if my number is lower, 1 if my number is higher, otherwise return 0
int guess(int num);

class Solution
{
public:
    int guessNumber(int n)
    {
        int low = 1;
        int high = n;
        int mid = (low + high) / 2;
        while(low <= high) {
            switch(guess(mid)) {
            case -1:
                high = mid - 1;
                break;
            case 1:
                low = mid + 1;
                break;
            case 0:
                return mid;
            }
            mid = (low / 2) + (high / 2) + ((low & 1) + (high & 1)) / 2;
        }
        return low;
    }
};

class Solution
{
public:
    int guessNumber(int n)
    {
        int low = 1;
        int high = n;
        int mid;
        while(low <= high) {
            mid = low + (high - low) / 2;
            switch(guess(mid)) {
            case -1:
                high = mid - 1;
                break;
            case 1:
                low = mid + 1;
                break;
            case 0:
                return mid;
            }
        }
        return low;
    }
};